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Author Topic: OQO tablet PC digitizer  (Read 15420 times)
Wilcorp70
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« on: May 12, 2011, 11:27:29 PM »

So my wife and I love wacom tablet pc's.  Recently, when she graduated from college she needed something more like a pda rather than a full blown laptop.  She really hates resistive screens and can't live without a pen or OneNote.  So the only compromise was an OQO 02http://www.oqo.com/products/model02/features.html; made with wacom's smallest digitizer, just 5 inches diagonally.  I've just gotten some extra parts for this tablet from another forum and I asked for a spare digitizer+screen.  It just came in the mail, and I am excited to try and interface this thing.  Im wondering if I get this hooked up to usb if I cant mount it behind a dell streak screen or something crazy.
 
My first problem; because of space, I'm pretty sure the company combined everything coming from the screen into two ribbon cables.  The one that comes from the digitizer has 34 PINS!  I think that number includes the control for the backlight and two capacitive touch scrollers.  Some people on Ebay have taken better pictures than me of this stuff and apparently my pictures are too big to attach, so here is a shot of the back of the screen and digitizer with the screen ribbon cable (this is not the digitizer ribbon cable, that plugs into the rectangular socket on the lower left):
http://cgi.ebay.com/ws/eBayISAPI.dll?VISuperSize&item=180657261148
The picture in this ad is just the digitizer and the backlight (notice again the plug for the ribbon cable):
http://cgi.ebay.com/OQO-Model-02-Replacement-LCD-Screen-Assembly-TESTED-/170616689755?pt=LH_DefaultDomain_0&hash=item27b98c145b#ht_736wt_901
And this is the digitizer ribbon cable alone:
http://cgi.ebay.com/OQO-Model-02-Internal-LCD-Ribbon-Cable-FPC-0043-01-/180640523414?pt=LH_DefaultDomain_0&hash=item2a0f03a496#ht_500wt_922
I have a cheap multimeter here at home, and access to an oscilloscope, but I have gaps in my electronics knowledge from being self taught (Im an aerospace engineer, not EE).  Any help would be appreciated.

~Will
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bernard
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« Reply #1 on: May 13, 2011, 02:18:56 AM »

hey Will,

Good to hear from you! ...and with quite a challenge!

That url for an ebay picture does not work "directly". The problem with ebay images is that they quickly stop working. If you could reduce the image size and attach it here it would be best, but anyway, I do not want to give you more work either...   I was able to find the item by its number and find the picture (it is still up).

What I see from the picture is the proof that it is indeed a wacom. Model number is SB-0503P-01X -- which suggests a size of 5 by 3 inches. -01X we often see this, it appears as some sort of version number + installed option, and the "SB" letters I do not recall seeing.

From the picture we only see that big orange flex pcb with that rectangle connector -- it is not clear from the picture if it is really connected to the wacom sensor (it appears not?).  I think you have to dig more:  find the wacom babyboard somewhere in there. Hopefully the Wacom babyboard is present -- if not, you are screwed. I mean, if that big flex pcb is actually the wacom sensor board (just folded) and there is absolutely no other circuitry, then we have a problem. Wacom sensors are just a big bunch of vertical and horizontal traces going accross on a PCB (flex or standard) (two layers)  -- there is nothing fancy!  Another important part is a metallic sheet right behind the sensor -- the type of metal, its distance from the sensor and its thickness is important.

"Access to an oscilloscope" -- oh! just that!  Tongue -- just out of curiosity, do you know the bandwidth of the scope?
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Trashie
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« Reply #2 on: May 13, 2011, 02:58:39 AM »

Let me ask you something first..What's what you're trying to do with that hardware?

If it's just experiment, woha..just accessing each pin will be fun..If there are 34 pins..My screen controller has 14 pins (the LCD controller board uses less than that), and my wacom digitizer has 14, even if it only uses 10.Even supposing all those are used, still there are 6 unknown pins.And, being so integrated, it could be for many things (on/off leds?disk activity?webcam?buttons?)...If you want to experiment, maybe the starting point would be the "rest" of the oqo hardware.I mean, if you have a complete oqo, dissasemble the screen, and in the motherboard side, measure voltages, and, in the oscilloscope, maybe detect what pins are video signals going to the screen.Then, experiment with the other pins...But, lol, well, i hope you've plenty of time.
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Wilcorp70
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« Reply #3 on: May 13, 2011, 04:56:48 AM »

Ok, first off, sorry about the picture thing, I thought I had changed all of those from the picture links to their individual ebay ads.  Apparently, the first one didn't get changed.  One key thing to note is that the three links are actually to different ads that show different parts of the assembly.  That first picture is a bit misleading, as it only shows the ribbon to the lcd.  The third one is just the ribbon that actually goes to the digitizer.  Now, this board is different than any of the others I have seen from Wacom.  Their is no daughterboard per se, instead there is a frame containing all of the electronics around the digitizer.  Now that being said there are still 34 pins on that rectangular socket, and that is a pain, but I have a feeling that the wires are probably grouped together.  So I just need to find the group of (probably/hopefully) 14 pins that deal with the digitizer.  As far as I can tell the things on the screen that this ribbon might connect to is an ambient light sensor, two touch scroll sensors, and the wacom. (thankfully, I don't have to deal with video signals)

I do have the full hardware to deal with, but my wife would probably object to too much time with her computer in pieces; that being said, Im sure I can get some time with it.  This is a little more than an experiment, someday my wife may not be able to find a pda with pen input, if I can make this usb than I can upgrade anything with a 5 inch screen.  As for the equipment I have available, there are some very nice electronics labs some friends will let me into that have more than I could ever need. 
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Trashie
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« Reply #4 on: May 13, 2011, 05:17:49 AM »

Hmm..Why do you say you dont have to deal with video signals? In one of the links, i only see one connector for the whole screen..do you see a separate connector for the video signals in yours?
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bernard
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« Reply #5 on: May 13, 2011, 05:27:16 AM »

Oooh OK -- are you saying that this is a working piece???  Trying to follow you here: Am I correct in saying that you want to see if this fully working device could be torn apart to recuperate the wacom sensor to fit another 5 inch screen?  Actually you want to answer the question if it is feasible without breaking the device, right?

My feeling here is: If you want to reverse engineer it, you will have to disassemble the stuff up to a "dangerous" level of breaking it and we will try to send power here and there which can be a little bit risky for an expensive toy (for which the warranty is now voided).  It would be nice to have a clear shot of the Wacom board -- with the Test points and all the silk marking on the board and the components markings.  This can help greatly.

It seems the two first URLs point to different ebay ads but they use the exact same picture of the back -- have you found a better picture? I am looking for the digitizer board. Are you sure the digitizer board is the one with the white rectangle connector on the side?  I now see the green PCB sensor sticking out on the edge with what looks like a connector under it.


* oqo.jpg (151.21 KB. 800x646 - viewed 487 times.)


A: LCD Connector -- not looking at this
B: It shows that this is the LCD since it appears to go in some deeper layer
C: The white rectangle connector -- the wacom connector you are talking about?
D: This looks like the PCB of the wacom sensor sticking out -- appears to be some sort of connector under there.

« Last Edit: May 13, 2011, 05:37:54 AM by bernard » Logged
Wilcorp70
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« Reply #6 on: May 13, 2011, 05:35:59 AM »

There are two ribbon cables, one comes from the lcd and the other plugs into that little rectangular socket around the side; there is only one cable (the lcd one) shown in that first ad.  The last ad is for the actual digitizer cable.
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bernard
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« Reply #7 on: May 13, 2011, 05:53:49 AM »

Found the so called board-on-the-side:  

OQO Model 02 LCD Screen Daughter Board PCB-9072-03


* oqo_3.jpg (31.96 KB. 415x303 - viewed 383 times.)


This is not a Wacom-made board: It is marked as "OQO". Although the name PCB-9072-03 look like a Wacom name (?)


* oqo_2.jpg (48.13 KB. 536x337 - viewed 483 times.)


A: Wacom sensor connector(?)
B: That wild connector that we wish we knew what it was -- look black instead of white in here
C: What's that? another connector?  Maybe to connect to the touch?

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Wilcorp70
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« Reply #8 on: May 13, 2011, 06:04:08 AM »

Ok, I guess I haven't been clear.  Its a problem I have when I have thought things through a lot, I forget other people cant read my mind.  So, I have a full working OQO and an extra screen assembly (everything shown in that picture you embedded but with the digitizer cable plugged into that connector which is not shown in the picture).  I also have some extra dead motherboards that I am trying to repair separately; that doesn't really matter right now, as they are currently broken.  
Point C is the socket I was talking about, it is on what I will call the babyboard of the digitizer.  Yes Point A is the lcd connector and at D the sensor board connects with the babyboard.  I will get some pictures of what I have tomorrow, there is an additional metal plate backing on mine that is removed in the ebay pictures making it easier to see the connectors.  
The warranty on this thing has been out for a while, considering it is about 5 years old now.  I have to dissassemble the unit to clean out the fan, I might be able to keep it open long enough to sniff some signals, while connected to the motherboard; depends on how much my wife bugs me about having her computer.  I would only be sending power to the extra disembodied screen so Im not worried about the device; I wouldn't be trying this if I only had the computer to work with.

**You replied while I was typing my response: The babyboard is made by OQO but contains all the wacom chips to run the digitizer.  I will try to follow the traces on those other boards to see if I can find which pins on the ribbon they correspond to when I dissassemble it tomorrow.  Mostly, I am concerned with that final ribbon connector that goes to the motherboard though.
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Wilcorp70
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« Reply #9 on: May 14, 2011, 05:08:58 AM »

So one complete disassembly of the OQO and the extra screen later.  I have to say, this machine is a feat of engineering, its like taking apart a silicon swiss watch.  It looks like they worked with their hardware partners VERY closely including Wacom.  Everything appears to be modular and fit together in the tightest way possible.  I don't think this thing could be made any smaller.

Here is what I have learned, the daughter board attaches directly to the digitizer at point A on your diagram like you thought.  Point B is where the cable to the motherboard connects.  Point C is one of the most interesting things on this board, it is the connector for the backlight; this board is also the inverter!  I find this especially interesting considering our problems with inverters and jitter. 

Here is the back of the digitizer, the back of the daughterboard has a small black "socket" where the touch scroll sensors connect.  It actually connects using pressure to hold the electrical connection together rather than snapping into place. 

* Optimized-back of digitizer.JPG (119.01 KB. 1200x800 - viewed 534 times.)


After taking it apart it looks like the bottom of the board is dedicated to the inverter and the touch scrollers and the top of the board is dedicated to the wacom controller.  I tried to trace where the paths were going, but it was incredibly difficult as its a multilayer board.  I can see that they are consolidating into different groups though. 

I tried to get pictures of the silkscreen as well as the traces, but no luck with my camera.  I just have a sony point and shoot; any tips would be appreciated.  I don't think the silkscreen would be too helpful, as the whole board is simply labeled with a 1 or two letter code indicating the part type and number on the board.  Example: r4 for a certain resistor; none of the signals like tx are labeled. 

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bernard
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« Reply #10 on: May 14, 2011, 06:11:08 AM »

It is indeed incredibly difficult to get nice pictures of PCBs.  I also had a sony point and shoot to do that (pictures from the "Wacom Science" thread). I used a small tripod to hold it. I did not use the flash but some other light from a carefully choosen angle that will do what I wanted.  I think it is good when you have lots of ambient light in the room -- or outside when there is plenty of light.

So try to get clear a picture of a section of the board -- namely the wacom section -- the chips themselves and the surrounding parts. We could maybe try to match parts from another board etc.  It appears clear now that OQO integrated the wacom babyboard in there.
« Last Edit: May 14, 2011, 02:37:57 PM by bernard » Logged
Wilcorp70
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« Reply #11 on: May 14, 2011, 05:06:42 PM »

I can at least report the chips on the wacom side of the board.  The first is the wacom w8001; I think this is the common chip for all tablet pc daughterboards.  There is a press release about it below but I couldn't find a datasheet.
http://www.wacom-components.com/english/news/20011207.html
The second chip is labeled wn101cf78 its a quad flat package chip (pins on all 4 sides).  I couldn't find any info on it, though I can apparently buy a minimum of a thousand from china.  The black box at the very top; just above the wacom chip is the ambient light sensor and I have no idea what the purpose of the metal clip or the white rectangle next to it would serve.
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bernard
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« Reply #12 on: May 14, 2011, 06:48:30 PM »

We won't find datasheets for those ICs.  The idea is to match a board with the same circuit on it and find where are the traces going.  You have a continuity tester (beep) with your multi-meter?  you can hold one probe on a pin and then "scan" the wacom portion to see which "group" of pins appears to be related to the wacom.  There is some chance that the pin is in the same "order" (they probably just "stacked" many connectors into one).  Common stuff like the power and ground would probably be merged and thus not available as a "separate" pin for each "device".
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Trashie
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« Reply #13 on: May 14, 2011, 08:50:22 PM »

Mmm..i hate to be the devils advocate here, but this is why i asked what was the reason of this research..
If the plan is being able to give pen input to another 5 inch device, you can expect the level of integration of that device to be nearly the same the OQO has (or worse, with all those system-on-a-chip IC's they're making).To be able to insert a digitizer inside other device of that size, you'd have to have room for the digitizer, room for the cabling needed for the interface digitizer-device, and a free internal usb port to connect that cabling...Of course, you can make a whole new case for the device,but that's also quite an adventure!

You could go other way;use the digitizer and screen as a secondary screen for a smaller device (i've been considering this option for my Trashtiq).Problems then are support for secondary screen on that device (moderately common feature nowadays, but also means the inclusion of an LCD controller in the game), and additional power for the monitor (possible too), but no question it's a way bigger device.

There's another option, just "sticking" the digitizer at the back of the device, and use an external USB port to connect it.Issues then would be the device insulation, and (maybe) having the batteries and all the circuitry between the LCD and the digitizer.

Any of those solutions suppose drivers for that digitizer exists for the OS running on the device.

Any other idea on how to be able to "transplant" that digitizer?

LOL, anyway, i'm a great defensor of doing the things just for the sake of it :-D.And still think a good starting point is in the motherboard; turning it on and, at least, looking which pins are input voltages/signals going into the screen.
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Wilcorp70
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« Reply #14 on: May 15, 2011, 03:49:48 AM »

Well, the devices I have been thinking about are the dell streak, the villiv n5, or the sony UX.  All of these have a 5 inch screen either exactly or almost exactly the same size as the OQO.  The board itself is almost paper thin, and Im not really worried about mounting it behind the screen.  The daughter board could be a little difficult but still not muc space is required.  Even if I had to expand the cases a couple of millimeters, that wouldn't be too hard.  The UX has plenty of spaces, and from what I can find the streak looks doable, dont know enough about the villiv but people find ways to stick touch controllers and bluetooth in these palmtops all the time.  If the digitizer is usb than I can wire it to a port directly; people do it all the time to make external dongles internal and even the streak has usb host.  If it is serial, that is a little more difficult, and I will have to figure that out when it comes down to it.  As for drivers, android has them, but they aren't the best developed currently.
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